4. FORMATION PROCESSES

The most general conclusion that can be drawn from a comparison of the
dynamical models with the data is that elliptical galaxies show a much
narrower range in structures and kinematics than allowed by the models. The
clearest examples are the similar light profiles and M / L values, the
Faber-Jackson relation, the regular isophote shapes of galaxies, the
correlations of v /
with luminosity and other parameters, the
relatively small kinematic misalignments, the color-magnitude relation
(193), etc.
These properties are most likely a result
of the formation process, and not the equilibrium dynamics. It should be noted
in this context that the role of instabilities has not been explored fully.

Our understanding of galaxy formation has not progressed sufficiently
to have resulted in a finite number of competing theories and predictions,
which can be compared in detail to the observations. Some elements of theories
and observations are usually pieced together, often without the basis of a
comprehensive model of galaxy formation. Given the lack of predictive
power for
physical processes involving gas dynamics and star formation, many of the
statements we can make are only qualitative.

A fundamental problem with any interpretation is the question of whether
ellipticals have dark halos, and if not, if that lack is due to stripping. If
ellipticals were born without dark halos, then they are very different from
spiral galaxies, and the similarity between bulges and ellipticals would only
be superficial. Without any good evidence for such a fundamental distinction,
it is probably best to assume that both types of galaxies have dark halos.